Terminal bushing.



J. E. MATEER. TERMINAL RUSHING. APPLIGATION FILED MAR. 2, 1912.

l, 1 29,500, Patented Feb. 23, 1915.

ATTORNEY vThe lower end,

UNITED sTATEs PATENT oEErcE.

JESSE E. MATEER, 0F WILKINSBURG, PENNSYLVANIA, ASSIGNOR TQ WESTINGHOUSE- ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

TERMINAL RUSHING.

Specification of Letters Patent.

Patented Feb. 23, 1915i Application filed March 2, 1912. y Serial'No. 681,275.

To all whom it may concern Be it known that I, JEssE E. MATEER, a citizen of the United States, and a resident of VVilkinsburg, inthe county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Terminal Bushings, of which the following is a specification. y

My invention relates to insulating bodies for use with electric apparatus, and it has special reference to such insulating sleeves or bushings as are utilized with very high voltage circuit breakers, transformers and other electric devices inclosed in metal tanks or casings and immersed in oil.

One object of my invention is to provide an insulating body of the aforesaid character, which shall be capable of sustaining or withstanding a high voltage, relative to the amount of insulating material employed in its structure and which, at the same time, shall be suitable for operation out of doors or under other adverse conditions.

Another object of my invention is to protect the lower end of a terminal bushing of the aforesaid character from being damaged by electric arcs within the tank or casing and impurities in the oil or other insulating fluid into which it extends.

In order to accomplish the aforesaid objective results, I prefer to utilize a bushing of the so-called condenser type, which is composed of alternate layers. of insulating and conducting materials and is substantially `cylindrical in form. A portion of the cylindrical body of the terminal bushing is surrounded by-a close-fitting metal sleeve. Its upper end, which is tapered, *is inclosed in a cylindrical sleeve which may either be composed of a single tubular insulator or of a series of flanged porcelain rings which are cemented togetherl and to the metal sleeves.

which is also tapered, is surrounded by a frusto-conical sleeve of porcelain or other insulating material which is impervious to Voil and 1s cemented 1n place,

forming a tight joint with the metal sleeve. Figure 1 of the accompanying drawings is a partially sectional elevation of a terminal bushing constructed in accordance with my invention. Fig. 2 is asimilar view of a modified terminal structure which also embodies my invention. Y

`Referring to Fig. 1 of the drawings,- a

cylindrical bushing having a body 1 and hanging flanges 7, an upper end cap 8 and a frusto-conical sleeve 9. The end cap 8 is provided at its lower edge with a rounded or beaded edge to preclude the concentration thereupon of electrostatic lines, as is well known in the art. Each of the rings 6 is preferably formed of porcelain or other hard insulating material and is provided with an annular projection 10, within its flange 7, which closely fits over and is cemented to the upper end of the ring next below.

The bushing is preferably of the condenser type and is composed of a plurality of layers of alternately insulating and conducting materials, which are wound on an inner met-al tube 11, to the upper end of which the cap 8 is secured.

The frusto-conical sleeve 9 is fitted loosely over the tapered end 3 of the bushing and is sealed in position and to the metal sleeve 5 by an insulating cement which is impervious to moisture and oil.

The metal cap 8 is provided with a projection 13 having a hole 14, which may be engaged by a crane hook or other means for handling the device and constitutes a terminal member of the bushing.

The tube 11 may be utilized as a conducting lead and transmit electric energy from the apparatus .within the tank or casing (not shown) to the terminal member, or a conducting wire or cable 15 may be threaded through the tube 11 and joined to the terminal member, as shown in Fig. 1. Its lower end may then be connected directly to the terminals of the apparatus with which the bushing is associated.

By filling the spaces within the sleeve 9 and the rings 6 with insulating gum or some other suitable sealing compound, air and moisture are excluded and the main bushing is rendered practically free from deteriora tion. This result is a particularly important one, if the insulating body is of the condenser type, because a corona is produced at each exposed edge of the conduct` ing plates and causes a relativelyrapid deterioration of the insulating structure.

The structure of Fig. 1 is particularly conductor 15.

well adapted for use with circuit breakers and transformers of the outdoor type and other `electric apparatus which is intended forv operation in the open air, since each of the joints between the insulating rings is completely overhung by one of the flanges 7.

In Fig. 2, the bushing having the body 1, which is composed of alternate layers of insulating and conducting materials and which has gradually tapering ends 2 and 3, is provided at one end thereof with a metallic cap 8a which extends laterally from the The cap 8 is rounded or convexly curved adjacent to its edges with respect to the surfaces of the bushing l, substantially as shown in the figure in order to preclude the concentration thereupon of electrostatic flow lines. A cylindrical insulating sleeve 16 embraces one end 2 of the body 1, and is interposed'between the cap 8 and the metal sleeve 5. The sleeve 16 is filled with a molded insulating compound or an insulating gum as .in the structure of Fig. 1, inv order to seal hermetically the eX- posed edges of the conducting layers which terminate at the surface of the tapered end 2. c

It is apparent that the inner or smaller diameter conducting layers embodied in the bushing 1 or those layers which are closest vto the conducting wire 15 or the tube 11,

have higher potentials imposed thereupon than those conducting layers which are more remote from the wire 15 or the tube 11. As a result, the dielectric stresses and potential gradients adjacent to the exposed edges of the inner conducting layers are substantially higher than those adjacent to the exposed edges of the outer conducting layers. ,To preclude the premature formation of corona at the exposed edges of the inner conducting layers on .the bushlng end 2, the thickness ofthe insulatmg coat1n 16 increases progressively toward `the en of the bushing. For this reason a cylindrical extension sealed to the tapered end 2 is particularly desirable when thebushlng is to be used for high voltage service conditions. Moreover, the cylindrically shaped insulating body, such as 16, is preferred because ofthe ease of manufacturing the same.

The terminal bushing of my invention may be adapted for a station outlet or to be used with a tank or casing containing air instead of oil, by making its'lower end correspond to the upper end ofthe structure shown in F ig. 2.

Structural modifications may, of course, be effected within the spirit and scope of my invention.

I claim as my invention:

1. An `insulating structure comprising av body which is composed of alternate layers of insulating and conducting materials and ing materials, a

which has-a tapered end and a hermetically of said body.

2. An insulating terminal bushing comprising'a substantially cylindrical body having gradually tapered ends and composed of alternate layers of insulatingand conductmetal sleeve fitted onto the cylindrical body, a hollowcylindrical eX- tension sealed over the one end of the body and a frusto-conical sleeve ofhard insulating material sealed over theptherendcf the body.

3. A terminal bushing for electric circuits comprising a substantially cylindrical body having tapered ends and 'composed of alternate layers of insulating and conducting materials, a metal nsleeve fitted onto the cylindrical body and insulating rings assembled end to end having overhanging flanges sealed to one end of the metal sleeve and to each other, a metal end ring whereby a segmental jacket is provided for one end of the insulating body and a frusto-conical sleeve of hard insulating material fitted over the opposite end of the body and sealed thereto and to the lower end of the metal sleeve.

4. terminal bushing for electric circuits compr1sing a substantially cylindrical body, a metal sleeve fitted onto the cylindrical body and insulating rings assembled end to end and sealed to one end of theibody and to one end of the metal sleeve, and a metal end cap for holding the insulating rings in position, whereby a segmental jacket is provided for the insulating body.

5. An insulating terminal bushin prismga substantially cylindrical boy havlng gradually tapered ends, a metal sleeve fitted onto the body and a hollow cylindrical extension sealed over one of the tapered ends of the body.

6. An insulating structure comprising a body composed of alternate layers of insulating and conducting materials and having a tapered end and a covering of insulating material embracing said tapered end for sealing the edges of the structure and burying the otherwise exposed edges of the conducting layers.

An insulating terminal bushing comprismg a substantially cylindrical body hav- 1ng gradually tapered ends and composed of alternate layers of insulating and conducting materials, and a coating of insulating material on theV tapered ends for sealing the edges of the structure and burying the otherwise exposed edges ofthe conducting layers.

8. An insulating structure comprising a body composed 'of alternate layers of insulating and conducting materials and havlng a tapered end, and a covering of insulating material embracing said tapered end for sealing the edges of the structure and buryend cap sealed over the l ing the otherwise exposed edges of the conducting layers, the thickness of said insulating covering varying along the length of the tapered end of said body.

9. An `insulating structure comprising a body composed of alternate layers of insulating and conducting materials and hav.- ing a tapered end, and a covering of insulat- 'ing material embracing said tapered end for sealing the edges of the structure and burying the otherwise exposed edges of the conducting layers, the thickness of said insulating covering progressively increasing toward the end portion of the tapered end of said body.

.10. An insulating structure comprising a body composed of alternate layers of insulating and conducting materials and having a tapered end, and a covering of insulating material embracing said tapered end for sealing the edges of the structure and burying the otherwise exposed edges of the conducting layers, the thickness of said insulatingcovering varying along the length of the tapered bushing and being greatest at the end portion of said body.

In testimony whereof, I have hereunto subscribed my name this 20th day of Feb., 1912.

JESSE E. MATEER.

Witnesses:

R. J. DEARBORN, B. B. HINES. 

